The importance of linage analysis in schizophrenia is universally acknowledged. Six large families at high risk for schizophrenia and two healthy families, consisting of a minimum of 50 members each, will be carefully interviewed for diagnostic determinations of DSM IIIR schizophrenia and for schizophrenia spectrum traits (which include traits subsumed under the DSM IIIR categories of schizotypal personality disorder, schizoid personality disorder, and paranoid personality disorder), and tested for eye movement dysfunctions (EMDs). Linkage between chromosomal markers and clinical schizophrenia will be investigated using RFLP techniques. Linkage analysis will be extended to include EMDs as well as schizophrenia, and the cosegregation of EMDs and the inferred schizophrenia gene will be investigated. In addition to conventional linkage analysis, the latent triat model, which regards schizophrenia as one phenotypic manifestation of a pleiotropic disorder, will be used to explore another solution to the linkage problem.